Speed reducing mechanism, drive device, and optical instrument

Abstract

A speed reducing mechanism includes: a driven member; and a decelerating member transmitting a drive force from an actuator to the driven member. The driven member includes an engagement pin. The decelerating member includes: a teeth portion engaging a rotor pinion portion serving as the drive force from the actuator; and a cam slot engaging the engagement pin. The decelerating member is rotatably supported and is formed into a sheet shape thinner than a face width of the rotor pinion portion.

1. A drive device comprising:
 a board including an opening; 
 a blade adjusting an aperture of the opening; and 
 a speed reducing mechanism including:
 a driven member; and 
 a decelerating member transmitting a drive force from an actuator to the driven member, 
 wherein: 
 the driven member includes an engagement pin; 
 the decelerating member includes:
 a teeth portion engaging a rotor pinion portion serving as the drive force from the actuator; and 
 a cam slot engaging the engagement pin; and 
 
 the decelerating member is rotatably supported and is formed into a sheet shape thinner than a face width of the rotor pinion portion; 
 
 wherein the drive force from the actuator is transmitted to the blade by engaging the engagement pin provided in the driven member with the cam slot provided in the decelerating member. 
 
     
     
       2. The speed reducing mechanism of  claim 1 , wherein the decelerating member is flexible. 
     
     
       3. The speed reducing mechanism of  claim 1 , wherein:
 the teeth portion is formed at a peripheral portion of the decelerating member; and 
 the cam slot is formed between the teeth portion and a rotation center of the decelerating member. 
 
     
     
       4. The drive device of  claim 1 , wherein at least a part of the decelerating member overlaps the driven member in an optical axis direction. 
     
     
       5. The drive device of  claim 1 , wherein at least a part of the decelerating member overlaps the blade in an optical axis direction. 
     
     
       6. The drive device of  claim 1 , wherein the decelerating member and the blade are arranged on an identical side with respect to the driven member. 
     
     
       7. An optical instrument comprising
 a drive device including:
 a board including an opening; 
 a blade adjusting an aperture of the opening; and 
 a speed reducing mechanism including:
 a driven member; and 
 a decelerating member transmitting a drive force from an actuator to the driven member, 
 wherein: 
 the driven member includes an engagement pin; 
 the decelerating member includes:
 a teeth portion engaging a rotor pinion portion serving as the drive force from the actuator; and 
 a cam slot engaging the engagement pin; and 
 
 the decelerating member is rotatably supported and is formed into a sheet shape thinner than a face width of the rotor pinion portion; 
 
 wherein the drive force from the actuator is transmitted to the blade by engaging the engagement pin provided in the driven member with the cam slot provided in the decelerating member.